Generate IPv6 SSH configuration to devices with IPv6 address configured

[saiarcot895]

Description of PR

Summary: Fixes # (issue)

Type of change

• [ ] Bug fix
• [x] Testbed and Framework(new/improvement)
• [ ] Test case(new/improvement)

Back port request

• [ ] 202012
• [ ] 202205
• [ ] 202305
• [ ] 202311
• [ ] 202405

Approach

What is the motivation for this PR?

Currently, the SSH configuration uses the IPv4 address of a device. However, devices may also have an IPv6 address available, and some tests may configure the device to only have an IPv6 address on eth0.

How did you do it?

Modify the SSH config generation to support generating a separate entry with the IPv6 address instead of the IPv4 address. These entries will have a suffix of -v6.

A separate entry approach was chosen partly because OpenSSH's config doesn't support using multiple literal IP addresses.

How did you verify/test it?

Tested the OpenSSH config generation, and it looks file. Have not tested the SecureCRT config generation.

Any platform specific information?

Supported testbed topology if it's a new test case?

Documentation

[wsycqyz]

Do we need this PR in 2024 or 2023 branch?

[saiarcot895]

@wsycqyz no, this PR is not required in older branches.